| 30841. |
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| 30842. |
- Olofsson, Martin, et al.
(författare)
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Baltic Sea microalgae transform cement flue gas into valuable biomass
- 2015
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Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 11, s. 227-233
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Tidskriftsartikel (refereegranskat)abstract
- We show high feasibility of using cement industrial flue gas as CO2 source for microalgal cultivation. The toxicity of cement flue gas (12-15% CO2) on algal biomass production and composition (lipids, proteins, carbohydrates) was tested using monocultures (Tetraselmis sp., green algae, Skeletonema marinoi, diatom) and natural brackish communities. The performance of a natural microalgal community dominated by spring diatoms was compared to a highly productive diatom monoculture S. marinoi fed with flue gas or air-CO2 mixture. Flue gas was not toxic to any of the microalgae tested. Instead we show high quality of microalgal biomass (lipids 20-30% DW, proteins 20-28% DW, carbohydrates 15-30% DW) and high production when cultivated with flue gas addition compared to CO2-air. Brackish Baltic Sea microalgal communities performed equally or better in terms of biomass quality and production than documented monocultures of diatom and green algae, often used in algal research and development. Hence, we conclude that microalgae should be included in biological solutions to transform waste into renewable resources in coastal waters. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 30843. |
- Olofsson, Martin, 1975-, et al.
(författare)
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Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata
- 2014
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Ingår i: Marine Drugs. - Basel, Switzerland : MDPI AG. - 1660-3397. ; 12:4, s. 1891-1910
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Tidskriftsartikel (refereegranskat)abstract
- Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.
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| 30844. |
- Olofsson, Martin, 1975-
(författare)
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Microalgae : future bioresource of the sea?
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Unicellular microalgae are a renewable bioresource that can meet the challenge forfood and energy in a growing world population. Using sunlight, CO2, nutrients,and water, algal cells produce biomass in the form of sugars, proteins and oils, allof which carry commercial value as food, feed and bioenergy. Flue gas CO2 andwastewater nutrients are inexpensive sources of carbon and fertilizers. Microalgaecan mitigate CO2 emissions and reduce nutrients from waste streams whileproducing valuable biomass.My focus was on some of the challenging aspects of cultivating microalgae ascrop: the response of biomass production and quality to seasonality, nutrients andbiological interactions. Approach spans from laboratory experiments to large-scaleoutdoor cultivation, using single microalgal strains and natural communities insouthern (Portugal) and northern (Sweden) Europe.Half of the seasonal variation in algal oil content was due to changes in light andtemperature in outdoor large-scale cultures of a commercial strain (Nannochloropsisoculata). Seasonal changes also influence algal oil composition with more neutrallipids stored in cells during high light and temperature. Nitrogen (N) stress usuallyenhances lipid storage but suppresses biomass production. Our manipulationshowed that N stress produced more lipids while retaining biomass. Thus,projecting annual biomass and oil yields requires accounting for both seasonalchanges and N stress to optimize lipid production in commercial applications.Baltic Sea microalgae proved to be a potential biological solution to reduce CO2emissions from cement flue gas with valuable biomass production. A multi-speciescultivation approach rather than single-species revealed that natural or constructedcommunities of microalgae can produce equivalent biomass quality. Diversecommunities of microalgae can offer resilience and stability due to more efficientresource utilization with less risk of contamination, less work and cost for culturemaintenance.Stable algal biomass production (annual basis) was achieved in outdoor pilot-scale(1600 L) cultivation of Baltic Sea natural communities using cement flue gas as aCO2 source. Results indicate favorable algal oil content at northern Europeanlatitudes compared to southern European latitudes.My thesis establishes the potential of cultivating microalgae as a bioresource inScandinavia, and using a community approach may be one step towardssustainable algal technology.
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| 30845. |
- Olofsson, Martin, 1975-, et al.
(författare)
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Production stability and biomass quality in microalgal cultivation : contribution of community dynamics
- 2019
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Ingår i: Engineering in Life Sciences. - Hoboken, NJ : John Wiley & Sons. - 1618-0240 .- 1618-2863. ; 19:5, s. 330-340
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Tidskriftsartikel (refereegranskat)abstract
- The prospect of using constructed communities of microalgae in algal cultivation wasconfirmed in this study. Three constructed communities of diatoms (Diatom), greenalgae (Green) and cyanobacteria (Cyano), were each mixed with a natural communityof microalgae as baseline. The communities were cultivated in batch and semicontinuousmode and fed CO2 or cement flue gas (12-15 % CO2). Diatom had thehighest growth rate but Green had the highest yield. Dynamic changes in thecommunity composition occurred from start through batch to semi-steady state. Greenalgae were the most competitive group during the experiment. Euglenoids wererecruited from scarce species in the natural community and became a large part of thebiomass in semi-steady state in all communities. High temporal and yield stabilitywas demonstrated in all communities during semi-steady state. Biochemicalcomposition (lipids, proteins and carbohydrates) was similar for the threecommunities with lipids ranging 14-26 % of dry weight (DW), proteins (15-28 %DW) and carbohydrates (9-23 % DW). Filamentous cyanobacteria were outcompetedearly in the experiment. However, their minute presence in Cyano associated withhigher lipid and lower carbohydrates compared to Diatom and Green, suggesting theimportance of chemical interactions among microorganisms. Our results indicate thatculture functions (stability, biomass quality) were maintained while dynamic changesoccurred in community composition. We propose that a multi-species communityapproach can aid sustainability in microalgal cultivation, through complementary useof resources and higher culture stability. Local environmental conditions,complementary microalgal traits, and interactions among functional groups (algae,bacteria) should be considered in community design where natural succession andcrop rotation will likely provide stability for commercial-scale algal cultivation.
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| 30846. |
- Olofsson, Martin, 1975-, et al.
(författare)
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Seasonal variation of lipids and fatty acids of the microalgae Nannochloropsis oculata grown in outdoor large-scale photobioreactors
- 2012
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 5:5, s. 1577-1592
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Tidskriftsartikel (refereegranskat)abstract
- While focus in oil-producing microalgae is normally on nutrient deficiency, weaddressed the seasonal variations of lipid content and composition in large-scalecultivation. Lipid content, fatty acid profiles and mono- di- and triglycerides (MAGs,DAGs, and TAGs) were analyzed during May 2007–May 2009 in Nannochloropsis oculatagrown outdoors in closed vertical flat panels photobioreactors. Total lipids (TL) rangedfrom 11% of dry weight (DW) in winter to 30% of DW in autumn. 50% of the variation inTL could be explained by light and temperature. As the highest lipid content was recordedduring autumn indicating an optimal, non-linear, response to light and temperature wehypothesize that enhanced thylakoid stacking under reduced light conditions resulted inmore structural lipids, concomitantly with the increase in glycerides due to releasedphoto-oxidative stress. The relative amount of monounsaturated fatty acids (MUFA)increased during autumn. This suggested a synthesis, either of structural fatty acids asMUFA, or a relative increase of C16:1 incorporated into TAGs and DAGs. Our resultsemphasize the significant role of environmental conditions governing lipid content and composition in microalgae that have to be considered for correct estimation of algal oilyields in biodiesel production.
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| 30847. |
- Olofsson, Ragnar, 1978-, et al.
(författare)
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Svenska förtidspensionärers levnadsförhållanden år 2000. : Redovisning av datamaterialet från en intervjuundersökning gjord år 2000
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport redovisas resultaten av en omfattande intervjuundersökning av svenska förtidspensionärer och deras levnadsvillkor som de såg ut år 2000. Undersökningen ingick som den svenska delen i det nordiska forskningsprojektet ”Unemployment, Early Retirement and Citizenship: Marginalisation and Integration in the Nordic Countrie”. Detta projekt leddes av professor Jørgen Goul Andersen vid Aalborgs universitet och det finansierades av NOS-S, dvs. Nordic Social Science Research Council (via anslaget REL/29). I projektgruppen ingick, förutom Jørgen Goul Andersen, Per H. Jensen (Danmark), Einar Øverbye (Norge), Laura Saurama (Finland) och Gunnar Olofsson (Sverige), I rapporten ges en utförlig översikt av datamaterialet i den svenska delen av NOS-S-projektets undersökning. Huvuddelen av framställningen utgörs av frekvenstabeller men också av en del diagram.Det är en detaljerad genomgång av alla variabler plus några nykonstruerade inom NOS-S-projektet; En jämförelse görs med ett motsvarande urval av respondenter i SCBs ULF-material. De flesta tabeller följs av kommentarer som rör resultaten och eventuellt intressanta iakttagelser och med förslag till vidare undersökningar. Kommentarer i kursiv stil innebär metodologiska och tekniska kommentarer kopplade till datamaterialet. Dessa delar av rapporten – ss. 7 – 118 – är skrivna av Ragnar Olofsson som också svarat för alla statistiska bearbetningar. Dessa delar av rapporten färdigställdes i december er 2003. Magnus Eriksson, som ansvarade för arbetet med datainsamlingen och som också kodade de öppna frågorna i enkäten, beskriver utförligt intervjuundersökningens tillkomst och genomförande i rapportens del IV, ”Teknisk Rapport”. Den följer efter dataredovisningens tre delar (se nedan ss. 119–124). Urvalspopulationen utgjordes av samtliga personer i Sverige mellan 55-64 år som arbetade år 1990 men som år 2000 hade sin huvudsakliga försörjning genom förtidspension och sjukpension. Svarsfrekvensen var hög, 75 %. Sist i rapporten redovisas fyra bilagor, förts och främst frågeformuläret som användes i undersökningen
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| 30848. |
- Olofsson, Tommy, 1950-
(författare)
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A New Gospel of Meaning
- 1992
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Ingår i: Literary Olympians 1992. - Boston, Massachusetts : Ford-Brown & Co.. - 0918644518 ; , s. 237-237
-
Bokkapitel (populärvet., debatt m.m.)
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| 30849. |
- Olofsson, Tommy, 1950-
(författare)
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A Portrait of the Artist as a Flying Man
- 1982
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Ingår i: Nordic Rejoycings 1982. - Gothenburg : The James Joyce Society of Sweden and Finland. - 9172607114 ; LXXVI:1, s. 3-41
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- An analysis of the symbolic pattern in James Joyce’s novel A Portrait of the Atrtist as a Young Man, focused on the dichtomy fly – fall.
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| 30850. |
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